Characteristics of carotid body chemosensitivity in NADPH oxidase-deficient mice
Characteristics of carotid body chemosensitivity in NADPH oxidase-deficient mice
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DOI：
10.1152/ajpcell.2002.282.1.c27
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发表时间：
2002-01-01
影响因子：
5.5
通讯作者：
Fidone, S
中科院分区：
文献类型：
--
作者：
He, L;Chen, J;Fidone, S
各种含血红素的蛋白质被认为是哺乳动物颈动脉体中I型缺氧敏感细胞的主要分子氧感受器。有一组数据特别支持中性粒细胞中常见的细胞色素b NADPH氧化酶的参与。这种酶的亚单位已经免疫细胞化学定位于I型细胞，而二苯基碘正离子，一种氧化酶的抑制剂，增加了颈动脉小体化学感受器的活性。本研究评估了正常小鼠和gp91吞噬细胞氧化酶(gp91(Phox))DNA序列基因敲除(KO)小鼠颈动脉小体的免疫细胞化学和功能特性，KO是编码中性形式NADPH氧化酶的一个亚单位的基因。酪氨酸羟基酶是I型细胞的标志性抗原，免疫组织化学染色显示细胞群或小叶具有其他物种中典型的O-2敏感细胞的形态特征，而酪氨酸羟基酶免疫阳性细胞在两个品系的小鼠颈动脉体中的发生率相似。对全细胞K+电流的研究也表明，在从正常动物和KO动物分离的I型细胞中，相同的电流-电压关系和低氧对电流的抑制。同样，缺氧引起的细胞内钙离子浓度的升高在正常和KO I型细胞中没有显著差异。通过记录体外颈动脉窦神经活动来评价整体器官对缺氧的反应。在这些实验中，低氧和经典的化学感受器刺激剂尼古丁引起的反应在正常和KO制剂中也是无法区分的。我们的数据表明，在gp91(Phox)基因序列中断后，颈动脉体部功能保持不变。这些发现与吞噬形式的NADPH氧化酶在动脉化学感受中作为主要的O2感受器的假设不一致。
Various heme-containing proteins have been proposed as primary molecular O-2 sensors for hypoxia-sensitive type I cells in the mammalian carotid body. One set of data in particular supports the involvement of a cytochrome b NADPH oxidase that is commonly found in neutrophils. Subunits of this enzyme have been immunocytochemically localized in type I cells, and diphenyleneiodonium, an inhibitor of the oxidase, increases carotid body chemoreceptor activity. The present study evaluated immunocytochemical and functional properties of carotid bodies from normal mice and from mice with a disrupted gp91 phagocytic oxidase (gp91(phox)) DNA sequence gene knockout (KO), a gene that codes for a subunit of the neutrophilic form of NADPH oxidase. Immunostaining for tyrosine hydroxylase, a signature marker antigen for type I cells, was found in groups or lobules of cells displaying morphological features typical of the O-2-sensitive cells in other species, and the incidence of tyrosine hydroxylase-immunopositive cells was similar in carotid bodies from both strains of mice. Studies of whole cell K+ currents also revealed identical current-voltage relationships and current depression by hypoxia in type I cells dissociated from normal vs. KO animals. Likewise, hypoxia-evoked increases in intracellular Ca2+ concentration were not significantly different for normal and KO type I cells. The whole organ response to hypoxia was evaluated in recordings of carotid sinus nerve activity in vitro. In these experiments, responses elicited by hypoxia and by the classic chemoreceptor stimulant nicotine were also indistinguishable in normal vs. KO preparations. Our data demonstrate that carotid body function remains intact after sequence disruption of the gp91(phox) gene. These findings are not in accord with the hypothesis that the phagocytic form of NADPH oxidase acts as a primary O2 sensor in arterial chemoreception.